1. Field of the Invention
The present invention relates to air filters, and more particularly, to air filters for use in connection with air intake velocity stacks for use with internal combustion engines. The invention has particular utility in connection with air intake velocity stacks for motorcycle engines, and will be described in connection with such utility, although other utilities are contemplated.
2. Prior Art
The improvement of carbureting devices has led to a number of highly sophisticated and expensive pieces of equipment which basically have the objective to increase the efficiency of the air-fuel mixture being delivered to a vehicle engine. The classical method of increasing power was to increase the manifold throat size of the carburetor to increase the air flow and thereby increase the available power. It was thought that an increase in throat and carburetor valve sizes would produce a comparable increase in power at the engine output. One of the approaches to increase power without increasing displacement was to obtain a higher charge to the air-fuel mix in the engine chamber. Many of the devices disclosed by the prior art sought to increase the charge of the air-fuel mix by increasing the throat size, but this had an inherent problem. However, merely increasing the throat size resulted in a corresponding drop in air flow speed which produced incomplete fuel atomization because the air flow through the carburetor was too slow.
One of the methods of moving the desired volume of air-fuel mix into the chamber of the engine is to adapt the throat diameter and shape of the air intake velocity stack to provide for proper air flow into the carburetor. To this end, various air intake velocity stacks have been developed to provide a proper balance between the shape of the air intake stack and the size of the throat to achieve the desired volume of air-fuel mix at an adequate air flow. Referring to FIGS. 1 and 2, typical prior art air intake velocity stack 10 comprises a lower throat section 11 and an upper bell-like terminus 12. Throat 11 is a substantially cylindrical section which integrally extends into terminus 12. The outer surface of throat section 11 is flanged at 14, and includes bolt holes 15 which permit the velocity stack to be bolted to a carburetor 16. Carburetor 16 as shown in FIG. 1 employs a mounting plate 17, having bolt holes 18 being cooperatively aligned with bolt holes 15 in plate 14. Carburetor 16 is of the conventional type, and employs a fuel metering mechanism (not shown) which includes liquid fuel tube and fuel-metering needle, float, choke plate, and the necessary springs to provide a resilient force necessary to control the fuel metering system of carburetor 16. The actual construction and operation of carburetor 16 is beyond the scope of this application, the operation thereof being substantially similar to that described in U.S. Pat. No. 3,709,469.
Carburetor 16 is coupled to the vehicle engine through the use of engine mounting fixture 24. The internal throat 22 of mounting fixture 24 is substantially aligned with throat 11 of the air intake velocity stack 10 to provide a consistent flow path when the air throttling mechanism is opened.
Typically, air intake velocity stacks have been run open, i.e. without filters. However, running a velocity stack open, i.e. leading directly to the carburetor, invites particulate intake into the engine of contaminants such as sand, pebbles, etc. which could ruin an engine. A flat, clip-on filter mesh, designed to clip on the flanged open end of the stack, is available commercially. However, such clip-on mesh filters reduce the effective cross-sectional area of the velocity stack, and thus the air-fuel mixture, and also clog quickly, further degrading engine performance. Also, many motorcycle owners do not like to use clip-on filters because the clip-on mesh detracts from the appearance of the highly chromed velocity stack.
Some motorcycle owners stuff steel wool mesh or the like into the velocity stack, for catching sand and other particles. However, steel wool mesh does not make a good filter, and is prone to being dislodged or vibrated out. Also, sand and other particles may drop into the carburetor, when the mesh is removed for cleaning or replacement, and thus, damage the engine.
The present invention seeks to solve the aforesaid and other problems of the prior art, by providing an air filter which is fully concealed within the velocity stacks so as to not detract from the appearance of the velocity stack while, at the same time, providing an effective open area which significantly exceeds the cross-sectional open area of the velocity stack, so as not to affect or degrade performance. In a preferred embodiment of the invention, the air filter has an effective open area which exceeds the cross-sectional open area of the velocity stack by at least about 50%, preferably at least about 100-200% or greater.
It is thus an object of the present invention to provide a particular filter which may be used in connection with an air intake velocity stack, which overcomes the aforesaid and other disadvantages of the prior art.
Another object of the present invention is to provide a filter for an air intake velocity stack which maximizes airflow to the carburetor.
Yet another object of the present invention is to provide a filter for an air intake velocity stack which is inexpensive and simple to fabricate, and which may easily and safely be removed for cleaning and/or replacement .